Conventional clipboards commonly consist of rectangular sheets of hardboard having spring-loaded hinged metal clips mounted along the upper edges thereof. Such clips are admittedly effective for holding papers and other sheet materials in place upon the boards; however, they have certain inherent disadvantages that tend to reduce the usefulness and ease of handling of the clipboards as a whole. For example, conventional clipboards almost defy stacking since the spring assemblies tip the overlying boards and tend to cause such boards to slide away from each other. For the same reason, papers placed on top of such a board may slide off of the board unless the clip is used to hold them in place, thereby necessitating use of the clip even in situations where only a momentary support for the sheet materials is desired.
The spring hinge assembly of a conventional clipboard also provides an obstruction to hand movement for persons whose writing style involves placement of their writing hand above the line (as frequently is the case with lefthanders), or for children, artists, and other users who may wish to rotate the board and position their hand directly over the area of the spring clip for the purpose of coloring, sketching, or otherwise marking the sheet materials held upon the board.
In addition to being awkward to use and inconvenient to store, conventional clipboards tend to be relatively expensive because of the multiple-component metal clip assemblies mounted upon such boards. Thus, even though a spring clip assembly does provide a relatively secure gripping means for sheet materials supported upon such a board, it carries with it numerous offsetting disadvantages.
The present invention is concerned with an improved clipboard which overcomes such disadvantages of conventional boards. Specifically, the clipboard of this invention is completely flat when unused, thereby facilitating storage, stacking, and handling; has gripping members formed integrally with the board, thereby reducing complexity and expense; is easily manipulated to raise the spring members for the insertion or release of sheet materials; provides L-shaped members which, partly because of their configuration, exert a relatively even clamping force upon the sheet materials to hold such materials in place and, when so used, do not project above such sheet materials to any appreciable extent, thereby avoiding interference with hand movement and permitting stacking of the boards even when loaded; and provides clamping members which include stop elements for helping to orient sheet materials into proper positions for clamping. Additionally, the spring members are independently operable, may be easily released for permitting selective removal of one or more sheets from a stack, and are oriented so that when a clamping member is manipulated by a finger or fingers (ordinarily the index finger) of one hand, other fingers of the same hand may be used simultaneously to support the clipboard and to urge the sheet materials into or out of position.
Briefly, the clipboard takes the form of a flat and generally rectangular board of rigid but still somewhat flexible material. A hard durable polymeric material such as an acrylonitrile-butadiene-styrene (ABS) copolymer of a thickness within the range of about 0.07 to 0.15 inches has been found particularly effective, but other materials and thicknesses may be used. One edge of the board, an edge that would be commonly referred to as the top edge, is provided with cutouts defining a pair of integral L-shaped spring members normally flush with the remainder of the board. Each L-shaped member has a first leg portion extending along the top edge of the board and a second leg portion projecting into the board away from the top edge. The second leg portion of each L-shaped member provides an undersurface engagable with the sheet materials supported upon the board. Each such second leg portion is generally elongated and, when elevated from the remainder of the board in its clamping position, extends along a line generally parallel with the board's surface.
The first leg portion--that is, the leg portion of each L-shaped member that extends along the board's upper edge--serves as a stop element to limit the extent of upward movement of a sheet of paper or other material as it is inserted beneath the clamping member. To lift each clamping member, the user simply holds the board by its upper corners and flexes the first leg portion of each member upwardly while at the same time using his (her) thumbs to slide the sheet material into or out of position with respect to the second leg portions of the L-shaped members.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings.